Paleo zucchini lasagna

I actually made this meal last week and put it in the freezer. I got it out tonight to have for dinner. This is a perfect meal to bring to someone, or to make ahead of time and pop in the oven for a easy dinner. 1 large onion 2 tblsp olive oil 1.5 cups chopped mushroom Toni's Salt and pepper 2 cloves garlic 2 lb ground beef 2 cans of diced tomatoes 1 6 oz can tomato paste 1 tsp garlic powder 4 zucchini, peeled and sliced like lasagna noodles Sauté onion, mushroom, garlic, and olive oil in skillet. After slightly browned add meat. Once meat is brown add tomatoes, tomato paste, garlic powder. Let simmer for 20 minutes. Layer in baking dish, zucchini, meat sauce until dish is full. Bake for 30-40 minutes at 350 or until warm all the way through.